County outline
Where Tompkins County is located
Area breakdown
Land accounts for 96.6% of Tompkins County’s measured area and water for 3.4%. Its combined area converts to 1,273.1 square kilometers or approximately 314,591 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 474.65 | 1,229.338 | 303,776 |
| Water | 16.898 | 43.766 | 10,814.7 |
| Total | 491.548 | 1,273.103 | 314,590.7 |
How Tompkins County compares
By original Census land area, Tompkins County ranks #46 of 62 in New York and #2170 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.726 times the New York county-equivalent median of 653.7 square miles. It accounts for 1% of the combined county land area in the state.
See the complete New York ranking · What counts as a county equivalent?
Population and density of Tompkins County
The Census Bureau estimates that 104,047 people lived in Tompkins County on July 1, 2025. That ranks #610 of 3,222 county equivalents nationally and #28 of 62 in New York. Since the April 1, 2020 estimates base of 105,735, the population has declined by 1,688 (−1.6%), compared with −1% for New York as a whole.
With 474.7 square miles of land, that is 219 people per square mile (85 per km²), placing Tompkins County #612 nationally for density and #22 in New York. The median county equivalent has 47 people per square mile; the New York median is 112. Put another way, there are about 2.9 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 105,508 | 102,567 | 104,177 | 104,453 | 104,394 | 104,047 |
| Change | — | −2,941 | +1,610 | +276 | −59 | −347 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Tompkins County
Tompkins County is divided into 10 cities and towns. In New York, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Ithaca city, with 33,632 residents (32.3% of the county). The largest by land is Dryden town, at 93.6 mi², or 19.7% of the county’s land. Among those with at least 1,000 residents in 2020, Ithaca city grew fastest since then (+4.8%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Ithaca cityCounty seat | 33,632 | +4.8% | 5.389 | 1.1% |
| Ithaca townCounty seat | 20,670 | −7.3% | 28.9 | 6.1% |
| Dryden town | 13,320 | −4.3% | 93.6 | 19.7% |
| Lansing town | 11,786 | +1.8% | 60.5 | 12.7% |
| Groton town | 5,397 | −5.7% | 49.4 | 10.4% |
| Newfield town | 4,832 | −5.8% | 58.8 | 12.4% |
| Ulysses town | 4,728 | −3.3% | 32.9 | 6.9% |
| Danby town | 3,268 | −4.2% | 53.6 | 11.3% |
| Enfield town | 3,230 | −4.1% | 36.7 | 7.7% |
| Caroline town | 3,184 | −4.6% | 54.8 | 11.5% |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Tompkins County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Tompkins County is a central county of the Ithaca, NY Metropolitan Statistical Area. Tompkins County is the area’s only county equivalent, so the metro area has the same 474.7 square miles of land. By combined land it ranks #364 of 393 metropolitan areas, and #361 by population. It belongs to the Ithaca-Cortland, NY Combined Statistical Area.
ZIP codes
18 ZIP Code Tabulation Areas have land in Tompkins County; 12 of them have most of their land inside the county, and the others mainly cover neighboring areas.
130451305313062130681307313092131021373613864148171485014853148541486714881148821488314886
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Tompkins County
Tompkins County shares a land border with 6 county equivalents. It has more land than 3 of them. The largest neighbor is Cayuga County (691.6 mi²) and the smallest is Seneca County (323.7 mi²). Together with its neighbors, Tompkins County forms a block of 3,243.2 mi² of land, of which it holds 14.6%.
| Bordering county equivalent | Land mi² | Size vs. Tompkins | Compare |
|---|---|---|---|
| Cayuga County | 691.6 | 1.5× larger | Compare |
| Tioga County | 518.8 | 1.1× larger | Compare |
| Cortland County | 498.8 | 1.1× larger | Compare |
| Chemung County | 407.3 | 1.2× smaller | Compare |
| Schuyler County | 328.3 | 1.4× smaller | Compare |
| Seneca County | 323.7 | 1.5× smaller | Compare |
How big is Tompkins County compared with U.S. states?
Tompkins County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.2 times as much. New York’s county land could hold about 99 areas the size of Tompkins County.
Another way to picture it: the same land area would fill a square about 21.8 miles (35.1 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Tompkins County?
Tompkins County has more land than 1,052 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Tompkins County at #2,214 nationally by total area, 44 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 3.4%, compared with a national county-equivalent median of 1.2% — 2.3 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Tompkins County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2169 | Carroll County, Virginia | 474.7 | Compare |
| #2170 | Tompkins County, New York | 474.7 | This county |
| #2171 | Cedar County, Missouri | 474.5 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 42.453073, -76.473489. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,229,336,935 m²; AWATER: 43,765,694 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Tompkins County?
Tompkins County, New York has 474.7 square miles (1,229.3 km²) of land and 16.9 square miles of water, for a total area of 491.5 square miles. It ranks #2170 of 3,222 U.S. county equivalents by land area.
Is Tompkins County the largest county in New York?
No. Tompkins County ranks #46 of 62 in New York by land area. The largest is St. Lawrence County, with 2,679.5 square miles of land.
What counties border Tompkins County?
Tompkins County shares a land border with Tioga County, Schuyler County, Cayuga County, Cortland County, Seneca County, and Chemung County.
What is the population of Tompkins County?
The Census Bureau estimates Tompkins County had 104,047 residents on July 1, 2025, ranking #610 of 3,222 county equivalents. That is 219 people per square mile of land.
What is the county seat of Tompkins County?
The county seat of Tompkins County is Ithaca.
What cities and towns are in Tompkins County?
Tompkins County has 10 county subdivisions (cities, towns and townships). The most populous five are Ithaca city, Ithaca town, Dryden town, Lansing town, and Groton town.
Is Tompkins County part of a metropolitan area?
Yes. It is a central county of the Ithaca, NY Metropolitan Statistical Area.
How many ZIP codes are in Tompkins County?
18 ZIP Code Tabulation Areas have land in Tompkins County, and 12 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Tompkins County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.2 times as much land.
How many acres of land are in Tompkins County?
The land measurement converts to approximately 303,776 acres. Including water, total area is approximately 314,591 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.